A liturgical color, not in use throughout the Church according to Roman Ritual, but used in some places at certain times. It is the color specially associated with Our Lady and indicates constancy, fidelity, genuineness, and aspiration, being significant, in the Levitical system, of the air.

In pre-Reformation England there was no general rule as to colors but blue was often used. The Exeter ordinal for 1327 prescribes blue for certain double feasts of saints. According to an inventory of Meaux Abbey, Yorkshire, 1396, feasts of virgins not martyrs were kept in sky blue. Blue was one of the colors for confessors. In the 14th century at Wells blue was used in Advent and on Ash Wednesday. Inventories of 18 of the pre-bendal churches of Saint Paul’s taken in 1458 show that out of 18 churches 10 had blue vestments, and out of 83 suits 11 were blue. An inventory of Saint Dunstan’s, Canterbury in 1500 includes a “best” vestment of blue.

According to a decree of the Congregation of Rites, 12 February1884, by special indult some dioceses of Spain must use blue vestments instead of white on the feast of the Immaculate Conception, during its octave, and during the year whenever the Mass of the Immaculate Conception is said. Mexico has the same privilege and also Lourdes, France.

In Colombia blue vestments were used by special privilege on the occasion of the Coronation of Our Lady of Chiquinquira at Bogota, to which city the statue was brought for the ceremony.

In heraldry and art blue can indicate heavenly love and the unveiling of truth.